Numerical study on spark characteristics and evolution of plasma jet igniter

In this paper, a compressible spark plasma simulation model with fully coupled electromagnetic, flow, and thermal multi-physics process is developed based on COMSOL, and the evolution of spark properties during the spark plasma development of embedded plasma jet igniter is investigated by combining high-speed ICCD experimental data. The results show that in the early stage of spark plasma discharge, strong electric field distortion occurs in the near cathode electrode area, current density and temperature rise sharply, which develop close to each other and subsequently form spark plasma discharge channels; during the discharge development period, under the continuous Joule heat deposition, the plasma channel temperature rises and volume expands, and the plasma high pressure channel formed has obvious 'shockwave-like' pressure interrupted surface with the surrounding environment, and the 'shockwave-like' pressure interrupted surface propagates and reflects in the igniter cavity, driving the plasma cluster to move outward. The energy is gradually dissipated as the spark cluster rolls outside the igniter cavity sucking in the surrounding cold air. The energy loss of the spark plasma comes mainly from the heat exchange with the surrounding environment and the partial stay in the igniter cavity of the ignition plasma cluster that fails to participate in the ignition.